I did them all in my 1 series and was happy with them. It's quite an investment of both time and money to get them installed, but it does transform the car. Really they only require replacement as an upgrade, not because they are worn. If your car has additional power, it is worth it. If you're a track junkie, it is worth it. Otherwise leave them alone as it will be a waste of money. The additional torque from even just software over works the rear suspension and the car cannot track straight. Just know that once you start to upgrade the parts, it never stops. The easiest and best way to upgrade them is to buy an M3. Trust me on that one!